Cans or containers used in the paint industry are subject to intense pressure build up after the container or can lid is sealed to same. Generally, the pressure build up is due to the paint carrier volatilizing and/or sudden drops thereby increasing the pressure inside the sealed can. Various attempts have been made to provide a can or lid design to accommodate the various forces which occurs in paint cans and creates failure of the cover to remain on the rim. Attempts to deal with this problem are illustrated in the Knize U.S. Pat. No. 3,770,161 issued Nov. 6, 1973 for Can or Container And Lid Therefor and Knize U.S. Pat. No. 3,799,338 issued Mar. 26, 1974 for Can Or Container And The Lid Therefor.
Another problem in the paint can industry is providing a lid for a can or container which provides a tight seal but also can be used several times, that is the lid can be removed and then resealed several times without degrading the effectiveness of the seal. Representative examples of prior art attempts to solve this problem are illustrated in Knize U.S. Pat. No. 3,868,041 issued Feb. 25, 1975 for Can Or Container With Resealable Lid as well as Knize U.S. Pat. No. 3,902,630 issued Sept. 2, 1975 for Can Or Container With Locking Lugs For Locking Resealable Lid, the present invention being an improvement of the last named patent.
Various synthetic organic resins such as polypropylene or polyethylene may offer significant advantages over metal and be more readily adaptable to paint cans or containers than metal cans or containers, and accordingly, new lid designs can be provided for these new plastic cans or containers.